Highly fluorinated organic compounds, such as perfluorocarbon compounds ("PFC") are well known to be chemically and pharmaceutically inert. They also have the capacity of dissolving, transporting and delivering biologically and chemically significant quantities of oxygen. These properties make them potentially useful as oxygen transport agents, "artificial bloods" or red blood cell substitutes, in the treatment of heart attack, stroke and other vascular obstructions, as adjuvants to coronary angioplasty, cancer radiation treatment and chemotherapy and as contrast agents for various biological imaging modalities, such as nuclear magnetic resonance, ultrasound, x-ray and positron emission tomography.
Neat fluorocarbon liquids, however, cannot be injected into the blood stream, because their hydrophobic character makes them immiscible in the blood. As a result, they may cause vascular obstruction and death when transported into small blood vessels. Accordingly, for medical uses that require intravascular injection, such highly fluorinated organic molecules must be dispersed as physiologically acceptable, aqueous emulsions. See, e.g., L. C. Clark, Jr. et al., "Emulsions of Perfluorinated Solvents for Intravascular Gas Transport", Fed. Proc., 34(6), pp. 1468-77 (1975); K. Yokoyama et al., "A Perfluorochemical Emulsion as an Oxygen Carrier", Artif. Organs (Cleve), 8(1), pp. 34-40 (1984); and U.S. Pat. Nos. 4,110,474 and 4,187,252.
To date the medical usefulness of such emulsions of highly fluorinated organic compounds as "artificial bloods", red blood cell substitutes, oxygen transport agents or contrast agents for biological imaging has not been as successful as hoped. This results from the fact that none of the prior fluorocarbon-containing emulsions satisfies all of requirements of a preferred "artifical blood" or oxygen transport agent.
These requirements include: